在c#.net winforms中保存变量的值

public partial class MainForm : Form
{
    private int myVariable; // 成员变量

    public MainForm()
    {
        InitializeComponent();
    }

    private void SaveButton_Click(object sender, EventArgs e)
    {
        myVariable = 10; // 保存变量的值
    }

    private void LoadButton_Click(object sender, EventArgs e)
    {
        MessageBox.Show(myVariable.ToString()); // 加载变量的值
    }
}

using System.Configuration;

public partial class MainForm : Form
{
    public MainForm()
    {
        InitializeComponent();
    }

    private void SaveButton_Click(object sender, EventArgs e)
    {
        Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
        config.AppSettings.Settings["myVariable"].Value = "10"; // 保存变量的值
        config.Save(ConfigurationSaveMode.Modified);
    }

    private void LoadButton_Click(object sender, EventArgs e)
    {
        string myVariable = ConfigurationManager.AppSettings["myVariable"]; // 加载变量的值
        MessageBox.Show(myVariable);
    }
}

using System.Data.SqlClient;

public partial class MainForm : Form
{
    private string connectionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password";

    public MainForm()
    {
        InitializeComponent();
    }

    private void SaveButton_Click(object sender, EventArgs e)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            SqlCommand command = new SqlCommand("INSERT INTO MyTable (VariableName, VariableValue) VALUES (@name, @value)", connection);
            command.Parameters.AddWithValue("@name", "myVariable");
            command.Parameters.AddWithValue("@value", "10");
            command.ExecuteNonQuery();
        }
    }

    private void LoadButton_Click(object sender, EventArgs e)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            SqlCommand command = new SqlCommand("SELECT VariableValue FROM MyTable WHERE VariableName = @name", connection);
            command.Parameters.AddWithValue("@name", "myVariable");
            string myVariable = command.ExecuteScalar().ToString();
            MessageBox.Show(myVariable);
        }
    }
}